Razafinjatovo Caroline Fanja, Stiehl Daniel, Deininger Eva, Rechsteiner Markus, Moch Holger, Schraml Peter
Department of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland.
Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
Oncotarget. 2017 Feb 7;8(6):10199-10212. doi: 10.18632/oncotarget.14372.
Clear cell Renal Cell Carcinoma (ccRCC) formation is connected to functional loss of the von Hippel-Lindau (VHL) gene. Recent data identified its gene product, pVHL, as a multifunctional adaptor protein which interacts with HIFα subunits but also with the tumor suppressor p53. p53 is hardly expressed and rarely mutated in most ccRCC. We showed that low and absent p53 expression correlated with the severity of VHL mutations in 262 analyzed ccRCC tissues. In contrast to nonsense and frameshift mutations which abrogate virtually all pVHL functions, missense mutations may rather influence one or few functions. Therefore, we focused on four VHL missense mutations, which affect the overlapping pVHL binding sites of p53 and Elongin C, by investigating their impact on HIFα degradation, p53 expression and signaling, as well as on cellular behavior using ccRCC cell lines and tissues. TP53 mRNA and its effector targets p21, Bax and Noxa, were altered both in engineered cell lines and in tumor tissues which carried the same missense mutations. Two of these mutations were not able to degrade HIFα whereas the remaining two mutations led to HIFα downregulation, suggesting the latter are p53 binding site-specific. The selected VHL missense mutations further enhanced tumor cell survival, but had no effects on cell proliferation. Whereas Sunitinib was able to efficiently reduce cell proliferation, Camptothecin was additionally able to increase apoptotic activity of the tumor cells. It is concluded that systematic characterization of the VHL mutation status may help optimizing targeted therapy for patients with metastatic ccRCC.
透明细胞肾细胞癌（ccRCC）的形成与冯·希佩尔-林道（VHL）基因的功能丧失有关。最近的数据表明，其基因产物pVHL是一种多功能衔接蛋白，它不仅与HIFα亚基相互作用，还与肿瘤抑制因子p53相互作用。在大多数ccRCC中，p53几乎不表达且很少发生突变。我们发现，在262例分析的ccRCC组织中，p53表达降低和缺失与VHL突变的严重程度相关。与几乎消除所有pVHL功能的无义突变和移码突变不同，错义突变可能只影响一种或几种功能。因此，我们通过研究四种VHL错义突变对HIFα降解、p53表达和信号传导以及使用ccRCC细胞系和组织对细胞行为的影响，来关注它们对p53和延伸蛋白C重叠pVHL结合位点的影响。TP53 mRNA及其效应靶点p21、Bax和Noxa在携带相同错义突变的工程细胞系和肿瘤组织中均发生了改变。其中两个突变无法降解HIFα，而其余两个突变导致HIFα下调，这表明后者具有p53结合位点特异性。所选的VHL错义突变进一步提高了肿瘤细胞的存活率，但对细胞增殖没有影响。舒尼替尼能够有效降低细胞增殖，而喜树碱还能够增加肿瘤细胞的凋亡活性。结论是，系统表征VHL突变状态可能有助于优化转移性ccRCC患者的靶向治疗。
